— Irritable bowel
syndrome (IBS) is a chronic condition of the gastrointestinal tract. Its
main symptoms are abdominal pain and altered bowel habits which have no
identifiable cause.

IBS is the most commonly diagnosed gastrointestinal condition, second
only to the common cold as a cause of absence from work. An estimated 10 to
20 percent of people in the general population experience symptoms of IBS,
but only about 15 percent of affected people seek medical help.

Several treatments and therapies are available for IBS. These can help
alleviate symptoms, but not cure the condition. The chronic nature of IBS
and the challenge of controlling its symptoms are frustrating for both
patients and doctors. Treatment is more likely to be successful when a
patient gathers information about IBS and works closely with their doctor to
tailor a treatment plan.

CAUSE OF IRRITABLE BOWEL SYNDROME — A number of theories as to the
origin of IBS have been proposed over the years, but despite intensive
research, no cause has been consistently identified.

One theory suggests that IBS is caused by abnormal contractions of the
colon (hence the term "spastic colon," which was previously
used to describe IBS). Vigorous contractions of the colon can cause
cramps, providing the rationale for some of the treatments of IBS, such
as antispasmodics and fiber (both of which help to regulate the
contractions of the colon). However, abnormal colonic motility does not
explain IBS in all patients, and it is unclear whether it is a symptom
or cause of the disorder.

The development of IBS following severe gastrointestinal infections
(such as those caused by Salmonella or Campylobacter) has been well
recognized for years. The mechanisms by which infections trigger the
development of IBS are not well understood. Most patients with IBS do
not have a history of having had one of these infections.

People with IBS in the general community have the same psychological
makeup as those without IBS. However, people with IBS who seek medical
help are more likely to suffer from anxiety and stress than those who do
not seek medical advice. It is known that stress and anxiety have a
number of effects on the intestine; thus, it is likely that anxiety and
stress worsen symptoms, but they are probably not the cause of symptoms.
Some studies have suggested that IBS is more common in people who have a
history of physical, verbal, or sexual abuse.

Food intolerances are almost universal in patients with IBS, raising
the possibility that IBS is caused by food sensitivity or allergy. This
theory has been difficult to prove, although it continues to be studied.
The best way to detect an association between symptoms of IBS and food
sensitivity is to eliminate certain food groups systematically (a
process called an elimination diet), which is usually best accomplished
under the supervision of a doctor or nutritionist. The danger in
eliminating foods in a nonsystematic way is that it can erroneously lead
people to eliminate important sources of nutrition from their diet. In
addition, unnecessary dietary restrictions can further worsen the
quality of life in patients who already have enough to cope with.

A number of foods are known to cause symptoms that can mimic or aggravate
IBS, including dairy products (which contain lactose), legumes (such as
beans), and cruciferous vegetables (such as broccoli, cauliflower, brussels
sprouts, and cabbage), which increase intestinal gas and can thereby cause
cramps. Several medications also have effects on the intestines, and thus
may be contributing to symptoms.

Many researchers believe that IBS may be caused by heightened
sensitivity of the intestines to normal sensations (so-called
"visceral hyperalgesia"). This theory proposes that nerves
carrying sensory messages from the bowel are overactive in people with
IBS, so that normal amounts of gas or movement in the gastrointestinal
tract are perceived as excessive and painful. In support of this theory
is the observation that some patients with severe IBS feel better when
treated with medications (such as low doses of imipramine or
nortriptyline) that decrease the sensations coming from the intestine.

SYMPTOMS OF IRRITABLE BOWEL SYNDROME — IBS usually begins in young
adulthood. Women are twice as likely as men to be diagnosed with IBS,
although this might reflect an increased willingness among women in the
United States and other western countries to seek medical advice for this
condition. In other countries (such as India), the diagnosis is equal among
men and women. The hallmark of IBS is abdominal pain in association with
altered bowel habits.

Abdominal pain — Abdominal pain is typically crampy, varying in
intensity, and located in the lower left abdomen. However, the nature,
severity, and location of pain can vary considerably from person to person.
Some people notice that emotional stress and eating worsen the pain, and
that defecation relieves the pain. Some women with IBS notice an association
between pain episodes and their menstrual cycle.

Altered bowel habits — Altered bowel habits are another hallmark of
IBS. These altered habits may include diarrhea, constipation, or alternating
diarrhea and constipation. If diarrhea is the more common pattern, the
condition is called diarrhea-predominant IBS; if constipation is the more
common pattern, the condition is called constipation-dominant IBS.

Diarrhea — The diarrhea of IBS is usually
characterized by frequent loose stools of small to moderate volume. Bowel
movements usually occur during the daytime, and most often in the morning or
after meals. Diarrhea is often preceded by a sense of extreme urgency and
followed by a feeling of incomplete evacuation. About one-half of people
with IBS also notice mucous discharge with diarrhea. Diarrhea occurring
during sleep is very uncommon in IBS and should alert to other possible
diagnoses.

Constipation — The constipation of IBS can last from
days to months. Stools are often hard and pellet-shaped. Sometimes people
experience a sensation of incomplete evacuation, even when the rectum is
empty. This faulty sensation can lead to straining, sitting on the toilet
for prolonged periods of time, and the use of enemas and laxatives for
relief.

Other gastrointestinal symptoms — Other gastrointestinal symptoms
commonly experienced in patients with IBS include bloating, gas, belching,
heartburn, reflux, difficulty swallowing, an early feeling of fullness with
eating, and nausea.

Symptoms outside the gastrointestinal tract — Non-gastrointestinal
symptoms may accompany the gastrointestinal symptoms of IBS. These symptoms
may include frequent and urgent urination, painful menstruation, and sexual
problems.

DIAGNOSIS OF IRRITABLE BOWEL SYNDROME — Several intestinal
disorders have symptoms that are similar to IBS. Examples include
malabsorption (abnormal absorption of nutrients), inflammatory bowel disease
(such as ulcerative colitis and Crohn's disease), and microscopic and
eosinophilic colitis (uncommon diseases associated with intestinal
inflammation). Because there is no single diagnostic test for IBS, most
doctors compare a person's symptoms to formal sets of diagnostic criteria
(such as the Rome or Manning criteria). However, these criteria do not
perfectly discriminate among people with IBS, people with other
gastrointestinal conditions, and healthy people. Thus, a medical history,
physical examination, and select tests can help to rule out other medical
conditions.

When choosing among the many available diagnostic tests, a doctor usually
considers the information that they can provide, the likelihood that a
person's symptoms are being caused by some other medical condition, the cost
of the test, and the safety of the test. It is important to establish a firm
diagnosis so that both you and your doctor are confident in the treatment
approach.

Medical history — The diagnosis of IBS begins with a comprehensive
medical history. The medical history will include a discussion of the
nature, duration, and severity of gastrointestinal and other symptoms.
Sometimes a medical history reveals that dietary factors or drugs are
actually causing a person's symptoms. Doctors routinely ask about past and
present physical or sexual abuse and psychologic stress because these
factors may have a role in IBS.

Physical examination — A thorough physical examination usually
reveals no abnormalities in people with IBS, but it can help detect or rule
out conditions that mimic IBS.

Tests — Most doctors order routine blood tests in people with
suspected IBS; these tests are usually normal, but they can help rule out
other medical conditions. Sometimes, based upon certain symptoms or other
factors in your medical history, a doctor will order thyroid function tests
and/or stool tests to check for certain other conditions. Some doctors also
order more invasive tests, such as sigmoidoscopy or colonoscopy, especially
in people over the age of 40 years. These tests allow for visual and
microscopic inspection of the inside of the colon.

TREATMENT OF IRRITABLE BOWEL SYNDROME — There are a number of
different treatments and therapies for IBS. Many of these measures can be
combined to effectively reduce the pain and other symptoms of IBS. Because
of the wide variability of symptoms in people with this condition, different
treatments and therapies work for different people. Treatment is usually a
long-term process; during this process, it is important to maintain good
communication with your doctor about your symptoms, your concerns, and any
psychologic and social issues that arise.

Monitoring — The first step in treating IBS may be close monitoring
of your symptoms, your daily habits, and any other factors that may affect
gastrointestinal function. This step can identify factors that worsen
symptoms in some people with IBS, such as lactose or other food intolerances
and stress. A daily diary can be helpful.

Dietary modification — As discussed above, people with IBS commonly
describe food intolerances. Many have already eliminated or avoid certain
foods known to aggravate their symptoms. The systematic elimination of
particular foods can be helpful to determine the relationship between the
food and symptoms. This strategy may be particularly useful in patients who
have eliminated multiple foods, a behavior which in itself can contribute to
the decreased quality of life experienced by many people with IBS.

Many doctors recommend the temporary elimination of dairy products, since
lactose intolerance is common and can cause symptoms similar to IBS or
aggravate IBS. People who avoid lactose should take dietary calcium
supplements.

Several foods are only partially digested in the intestines. When they
reach the colon, further digestion takes place by bacteria, which produce
gas as a byproduct of their digestion. As a result, these foods can cause
gas and cramps. The most common are the legumes (such as beans) and
cruciferous vegetables (ie, vegetables that have a cross at their base) such
as cabbage, brussels sprouts, cauliflower, and broccoli. In addition, some
patients have trouble with onions, celery, carrots, raisins, bananas,
apricots, prunes, sprouts, and wheat.

Increasing dietary fiber — Increasing dietary fiber
(either by adding certain foods to the diet or using fiber supplements) can
relieve symptoms in some people with IBS, particularly people who have
combined abdominal pain and constipation. It may also be helpful in people
with diarrhea predominant symptoms since it can improve the consistency of
stools. It is often helpful to take a dietary fiber supplement (such as
psyllium [Metamucil] or methylcellulose [Citrucel]) since it is difficult to
consume enough fiber in the diet, particularly when avoiding foods known to
increase intestinal gas. Dietary fiber supplements should be increased to
the prescribed dose over several weeks to help reduce the symptoms of
excessive intestinal gas, which can occur in some people when beginning
fiber therapy. The reasons that fiber helps people with IBS are not
completely understood.

Psychosocial therapies — Stress and anxiety can worsen IBS in some
people. The best approach for reducing stress and anxiety depends upon the
individual and the severity of symptoms. You should have an open discussion
with your doctor about the possible role that stress and anxiety could be
having on your symptoms, and together decide upon the best course of action
for you.

Some patients benefit from formal counseling with or without
pharmacologic therapy or other treatments such as hypnosis and
biofeedback.

Participation in a support group can also be valuable.

Many patients find that daily exercise can be extremely helpful to
their sense of well-being. Exercise can also have favorable effects on
bowel action.

Drugs — Although many drugs are available to treat the symptoms of
IBS, these drugs do not cure the condition, and they are used primarily to
support other types of treatment. The choice among these drugs depends in
part upon whether a person has diarrhea, constipation, or pain predominant
IBS. Furthermore, the effectiveness of specific drugs varies from one person
to another. As a general rule, drugs are reserved for patients whose
symptoms have not adequately responded to more conservative measures such as
changes in diet and fiber supplementation.

Anticholinergic drugs — Anticholinergic drugs block
the nervous system's stimulation of the gastrointestinal tract and thus have
an antispasmodic effect, relieving severe cramping and irregular
contractions of the colon. Drugs in this category include dicyclomine (Bentyl)
and hyoscyamine (Levsin). These drugs may be particularly helpful when taken
prophylactically (ie, before symptoms) and thus are most helpful for
patients who can predict the onset of their symptoms. Common side-effects
include dry mouth and eyes and blurred vision.

Antidepressants — Many antidepressants have a pain
relieving effect that is independent of their depression relieving effect.
The pain relieving effect can often be observed at doses that are too low to
have an antidepressant effect. These drugs can alleviate the abdominal pain
of IBS, although they typically require three to four weeks to take effect.
One class of antidepressants, tricyclic antidepressants, which includes
amitriptyline, imipramine, and nortriptyline, also slow movement of contents
through the gastrointestinal tract and may be most helpful in people with
diarrhea predominant IBS. Another class of antidepressants, the selective
serotonin reuptake inhibitors, including the drugs paroxetine (Paxil),
fluoxetine (Prozac), sertraline (Zoloft), and citralopram (Celexa), are
usually prescribed for people who have both IBS and depression.

Antidiarrheal drugs — The drugs loperamide (Imodium)
or diphenoxylate with atropine (Lomotil) can help slow the movement of
contents through the gastrointestinal tract. Loperamide and diphenoxylate/atropine
are most helpful in people with diarrhea predominant IBS. However, doctors
usually recommend that these drugs should only be used as needed, and rarely
on a continuous basis.

Anxiolytic drugs — Anxiolytic drugs reduce anxiety.
Diazepam (Valium) belongs to this class of drugs. Anxiolytic drugs are
occasionally prescribed for people with IBS who are experiencing acute
anxiety that is worsening their symptoms. However, these drugs should only
be taken for short periods of time since they interact with other drugs, and
cause addiction and withdrawal syndromes.

Drugs affecting serotonin receptors — Serotonin is a
hormone that is involved in intestinal contractions and sensation. Drugs
that stimulate the serotonin receptors increase intestinal contractions
while drugs that block them decrease intestinal contractions.

The blocking category of these drugs is best suited for people with
diarrhea-predominant symptoms. The first that received approval from the
Food and Drug Administration was alosetron (Lotronex). However, alosetron
was withdrawn from the market soon after its introduction because of
concerns related to its safety. It was later reintroduced under tight
regulatory control. Whether other drugs in this class will prove to be safer
remains to be determined.

Tegaserod (Zelnorm) is the first of the stimulating category of drugs to
be approved by the Food and Drug Administration. In clinical trials, it
appeared to be moderately effective for patients with
constipation-predominant symptoms.

Drugs in development — Several new classes of
medications for IBS are currently in development. Their efficacy and safety
compared to other treatments that are already available remains to be
determined.

HERBS AND NATURAL THERAPIES — A number of herbal and natural
therapies have been advocated for the treatment of IBS. Unfortunately,
evidence supporting their benefit from scientifically conducted studies is
lacking. It is important to appreciate that even though small studies exist
that support a benefit of many of these therapies, the studies are either
too small or have major flaws that make definitive conclusions impossible.

Peppermint oil — There is a small amount of evidence supporting a
benefit for peppermint oil, although it is difficult to make definitive
conclusions. Peppermint oil can cause or worsen heartburn.

Acidophilus — There is increasing interest in the possible
beneficial effects of so called "healthy" bacteria in a variety of
intestinal diseases including IBS. Whether supplements containing these
bacteria (such as acidophilus with or without "FOS" or
Lactobacillus) are of any benefit is unproven.

Chamomile tea — Chamomile tea is of unproven benefit in IBS.
Furthermore, chamomile can aggravate allergies in people who tend to be
allergic. People allergic to the grass family can have an allergic reaction
to chamomile as well.

Wormwood — Wormwood is of unproven benefit and may be unsafe.
Wormwood oil can cause damage to the nervous system.

Comfrey — Comfrey is of unproven benefit and can cause serious
liver problems.

PROGNOSIS — Although IBS can produce substantial physical
discomfort and emotional distress, studies show that most people with IBS do
not develop serious long-term health conditions. Furthermore, the vast
majority of patients learn to control their symptoms with improved quality
of life.

Over time, less than 5 percent of people originally diagnosed with IBS
will be diagnosed with some other gastrointestinal condition, so it is
important to work with your doctor to monitor your symptoms over time.
Further testing might be required if your symptoms have changed. On the
other hand, studies also show that IBS does not decrease life expectancy;
people with IBS live just as long as people in the general population.